Up until now, ticklishness has been a mysterious physical sensation. Michael Brecht, professor at the Humboldt University of Berlin and Animal Physiologist, headed a research project along with Shimpei Ishiyama to help understand the sensation of tickling. Many questions have been asked about this mysterious physical sensation for many years without sparking answers. Even Aristotle and Charles Darwin were curious about tickling. Why are certain body part more ticklish than other? Why does the body react with smiles and laughter? Why can you not tickle yourself? Can other animals be ticklish as well?
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Turns out, rats are ticklish too! (Click HERE for video!) In the Study, Brecht and Ishiyama, tickled the rats. The subjects responded really well to the researchers tickling them, emitting “laughter-calls” and playfully chasing the the researcher’s hand. The calls are ultrasonic and can not be heard by the naked human ear. According to their laughter calls and the “unsolicited joy jumps” after being tickled, the rats are most ticklish on their bellies and on the bottom of their feet. Brecht observes, “It’s remarkable the similarities between rats and humans – the fact they vocalise and clearly enjoy tickling so much.”
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To further the research, Brecht and Ishiyama studied the brain to see what area of the brain reacts to tickling. Cells are activated in the somatosensory cortex of the brain causing the rats to giggle. The somatosensory cortex is part of the brain that registers touch and Brecht remarks that “we managed to pinpoint the ticklish spot in the brain.” During this study, they were able to discover that rats ticklishness is dependent on their mood. Rats response to being tickled was far less measurable when the rats were stressed This finding could lead to very important future research on the brain because there has been little research about how moods affects the brain.